Hefferon was born in Newbury, Berkshire, England, to an Irish father and an English mother but moved with his family to Canada and was raised on a farm near Brandon, Manitoba.

[2] He competed for South Africa in the 1908 Summer Olympics held in London, Great Britain in the marathon where he won the silver medal in the race famous for the dramatic finish of Dorando Pietri.

Hefferon was leading until the last mile and a half, when he lost ground after accepting a drink of champagne and being patted on the back by a well-wisher in the crowd.

He was overtaken by Pietri, who was subsequently disqualified for being helped over the line, and by the eventual winner, Johnny Hayes of the United States.

He worked on special assignments in Hamilton and then transferred to motorcycle patrol with the Department of Highways in Brantford, Blenheim, and starting in 1930 in Brampton.